Reduction gear



March l, 1932, F, HQDGKlNsON Y 1,847,611

REDUCTION GEAR Filed May 26, 1930 i. mi!` WITNESS 'afs' F 16,2 lNvENToR 3l E Frgzczs Hodgkmaon.

ATTORNEY Patented Mar. 1, 1932 nANor's noneKNseN, or rnitniinrrferrn, rnNNsStvnirIainssIeNon 'ro vvEsTING- Honsn nLEoTRoa MANUFACTURING VANIA Y COMPANY, A CORPORATION or rENNsYL- rinmi'ocnron GEAR My. invention relates to'power-transmission gearing and it has foran object to provide durable apparatus of this character capable of transni'itting' la'rge'loadsv and of accommodatingthe gear elements relatively to each other to maintain proper tooth engagement.

It is wellknown that gears having an enveloping form of teeth, such as cycloidal, are vcapable of operating with much'higher tooth loads than gears having teeth of involute form .because the curvature of the contours 'of the teeth in the former case more nearly correspond to each otherand the line of contact is abroader one. Furthermore, with the first-mentioned type of gear, the form of tooth is strongerwith the result that there is less deflection of the teeth under load. In general, I prefer to use the cycloidal'form of 'tootli, and the pit'chline may be placed in any relation with respect to the tooth, that is',- the teeth may bevpartially addendum and dedendum or wholly addendum. An objection to the use of the kenveloping or cycloidal form of tooth in large (gears is that, for proper operation; ythe teeth must remain at all times" in a definite depth of engagement. It is diiiicnlt to secure proper engagement, particiilarly'with largeA gears, because, with different expansions, duetolieat, of the gears and of supporting structures, it is mp'ossible to maintain proper tooth engagement vat all-times when the supports for the gears are rigid` with the supporting construction or frame.` Accordingly, therefore, it is a more particular object of my invention to provide means for automatically varying the centers between gear and pinion members so that the depth of interme'shing of the teeth vwillbefthe predetermined amountre'gardless f varying temperatures andexpansion of the gear and` pinion members and the suporting structure' therefor g, and, whileV means ofv tliis character is particularly suitable to maintain gear elements of the 'cycloidal form inpr'opermeshing relation,it is to be iinderstood that the present invention is not limited to any particular tooth form. l

These and other objects are effected by my Sinvention,A as will be apparent from. the following description and claimstaken in con- 1930. Serial No. 455,853.

Fig.2 is a detail view showingmeshing gear elements; I l f y Fig. 3 is a view, similar to Fig. l, but showing an alternative embodiment of my invention; and, Y

Fig. 4 is a detail view showing an example of enveloping cycloidalteeth. Y

Referring now to the drawings morein detail, I show a pinion 10 having teeth v11 meshing with teeth 12 on the gear 13. The meshing teeth are preferably of the'cycloidal or enveloping forni (Fig. 4) to providel for stronger teeth and therefore stronger gears.

As cycloidal gears should have predetermined relative positions to secure proper meshing relation, that is, the pitch circles rshould bev tangent, I provide the pinion y10 with shrouds or tires lyvhich engage with shrouds or tires 16 ofvthegear 13 to limit the depth of engagement of thet'eeth ll-relative- 1y to the teeth 12. The pinion 10 and the Y* b casing 17;

In order to maintain proper depth of engagement of the pinion and gear teeth with 'the tires or shronds in rolling 'contact and vwith expansion and contraction ofthe pinion and gear. members, the` supporting structure for the pinion andgearinembers is arranged to provide for movement of the pinion in- Oear 12 are 'carried by a suitable frame or wardly or outwardly with respect to the'aXis i Figs. 1 and 3, and permitting of inward or outwardv movement of the frame' to `take care of expansion and contraction enects ofthe gear members, it is necessary toprovide yieldable means cooperating withfthe frame to urge the latter toward the aXis of the gear so as to adjusted by the screw 23 so that the required force may be exerted on the trame to secure proper meshing relation of the pinion and gear teeth.

Instead of a spring, Iinay employ a pressure-responsive piston to provide the torce to A maintain proper meshing relation with the shroudrings or tires in rolling contact, the fluid therefor being either liquid or gaseous and supplied from any7 suitable source. In Fig. 3, the pinion frame 18 is pivoted at its lower side at 21 and the upper part of the traine contacts with a piston rod 24C connected to a piston 25 arranged in the cylinder 26. Means is provided for supplying fluid Linder pressure to the cylinder to automatically maintain the pressure therein approximately proportional to the load. In Fig. 3, this is accomplished by having a passage 27 connected to the cylinder and to the iilm pressure zone of. one or more of the pinion bearings, it being understood that the lub 1icating oil film pressure in the bearings is proportional to the reaction on the bearings and to the tooth pressure. Hence, with the form shown in Fig. 3, variable force is exerted to maintain the pinion in proper meshing relation with the gear. At light loads, when the force tending to spread the pinion and the gear about is not so great, the pressure exerted on the piston 25 is correspondingly reduced. Gn

the other hand, if the load increases, the force tending to separate the pinion and gear also increases but the latter force is counteract-ed by the increasing fluid pressure :torce exerted on the piston 25.

It' desired, means may be incorporated to provide a floating frame for the pinion 10. In Fig. 1, I show flexible supportor l-beam elements 30, 30 capable of providing for tilting about an yaxis transverse to the pinion axis. Also, I prefer to use a flexible quill drive for the pinion 10, the latter being made hollow and having the shaft 31 extending therethrough and coupled thereto at 32.

From the foregoing, it will be apparent that Y I have devised a pinion support which is capable of movement to maintain proper meshing relation cfa meshing pinion and gear. The pinion support is movable to maintain a uniform depth of engagement or the teeth l with expansion and contraction of the pinion and gear members, shroud rings or tires preierably being employed to limit the depth of engagement and yielding means cooperating Y with the pinion support to assure maintenance of proper meshing relation with the shroud rings or tires in rolling contact.

While I have shown my invention in two forms, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various other changes-and inocliications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or vas are speciiically set forth in the appended claims'.

What I claim is:

1.*In combination, in power-transinission gearing, a frame, a gear carried by said trame, a pinion meshing with the gear, a frame for the pinion, means providingior movement of the frame so that the pinion .may move toward or away from the gear axis, a pistonfor exerting force on the frame tending to move the pinion toward the gear member axis, and means for supplying fluid under pressure to act on said piston.

2. In combination, in power-transmission bearing, a supporting frame, a gear carried by said frame, a pinion meshing with said gear, a frame for said pinion, contacting shroud rings carried by the pinion and the gear for limiting the Ydepth of engagement of the teeth, means carried by the supporting frame and cooperating with the pinion frame to provide for movement of the latter toward and away from the axis of the gear, a piston for applying force to the pinion frame tending to move the pinion toward the gear, a cylinder for the piston and carried by said ysupporting frame, and means for supplying lubricant under pressure to said cylinder to exert pressure on the piston.

3. In combination, in power-transmission gearing, a supporting traine, a gear carried by said frame, a pinion meshing with the gear, shroud rings carried by the pinion and gear for limiting the depth of engagement f of thelteeth, a frame for the pinion, means providing for movement of the rameso that the` pinionmay move toward or away from the gear axis, pressure-responsive means for exerting force on said traine tending to move the pinion toward the gear, and means for'.

supplying lubricant from the hlm pressure zone ofthe pinion bearing to said pressureresponsive means.

4. In reduction gearing, a driven gear, a pinion meshing with the driven gear, shroud rings carried by the gear and by the pinion for limiting the depth of meshing engagement, a casing enclosing the driven gear and the pinion and supporting the driven gear,

a frame supporting the pinion, a floatingframe connection between the lower portion of the frame and the casing, and yieldable means effective between the casing and the upper portion of the frame above the pinion for ymaintaining therdepth of meshing en gagement of the gear and pinion, whereby the gea-r and the pinion are maintained in proper meshing relation irrespective of expansion and contraction effects.

5. In reduction gearing, a driven gear, a pinion meshing with the driven gear, shroud rings carried by the gear and by the pinion for limiting the depth of meshing engagement, a casing enclosing the driven gear and the pinion and supporting the driven gear, a frame supporting the pinion, a iioating frame connection between the lower portion of the frame and the casing, yieldable means interposed between the casing and the upper portion of the frame above the pinion for maintaining the depth of engagement of the pinion and the driven gear, and means providing for variation of the force exerted by said yieldable means.

6. In reduction gearing, a driven gear, a pinion meshing with the driven gear, shroud rings carried by the gear and by the pinion for limiting the depth of meshing engagement, a casing enclosing the driven gear and the pinion and supporting the driven gear, a frame supporting the pinion, a floating frame connection between the lower portion of the frame and the casing, a spring interposed between the casing and the upper portion of the :trame -above the pinion fogl maintaining the depth of vengagement of the pinion with the driven gear, and means for adjusting the compression of said spring.

7. In reduction gearing, a driven gear, a pinion meshing with the driven gear, the meshing teeth of the gear and of the pinion being of the envelopingtype, shroud rings carried by the gear and by the pinion for limiting the depth of meshing engagement, a casing enclosing the driven gear and the pinion and supporting the driven gear, a frame supporting the pinion, a floating frame connection between the lower portion of the frame and the casing, and yielding means eliective between the casing and the upper portion of the frame above the pinion for maintaining the depth of engagement of theV pinion and gear, whereby the pinion and gear are maintained in proper meshing relation irrespective of expansion and contraction ef-y fects.

In testimony whereof, I have hereunto subscribed my name this 23rd day of May, 1930.

FRANCIS HODGKINSON. 

